The invention refers to a laser applicator comprising an optical fiber that extends in a strand-shaped sheath and comprises a lateral decoupling area in a distal end portion, the sheath being formed as a loop in the area of the end portion, wherein the plane of the loop extends transverse to the major part of the sheath.
Atrial fibrillation is the most frequent cardiac arrhythmia in Europe and North America, afflicting more than every 15th human older than 60 years of age. Electric excitation waves are generated in the cardiac vestibules (atria) that propagate chaotically and impair the pumping function of the heart. Typical medical conditions are subjectively felt cardiac arrhythmias, tachycardia and a limitation of the physical load capacity, dizziness and fainting spells. Without a therapy, strokes will occur, often with serious and even fatal consequences, since blood clots can form due to an insufficient movement of the cardiac wall during atrial fibrillation, which may cause embolisms.
Methods using catheters to treat atrial fibrillation offer a chance for a permanent success of the therapy without requiring further permanent medication. Here, the source of the arrhythmia is searched for in heart using a thin flexible catheter and is then sclerosed.
In methods using catheters, certain electrically active regions of the atrial tissue are approached and obliterated by applying current. Eliminating or isolating these regions can prevent the occurrence of atrial fibrillation in 60%-80% of the cases. To achieve this, multiple punctual applications of current are used to form circular scars in the left atrium, which electrically insulate the affected cardiac tissue from the rest. This method is called “pulmonary vein isolation”. A conventional catheter is first advanced into the right atrium. In order to reach the left side, the interatrial septum is pierced (transeptal puncture). By limiting the conventional catheters to punctual lesions, an isolation line is formed by points that must be assembled to form circles in a three-dimensional space under two-dimensional X-ray control, without leaving gaps or injuring healthy tissue. More recent techniques aim at obtaining circular lesions around the pulmonary veins using balloon systems that are expanded at the pulmonary veins and extend into the same. The energy (ultrasound, laser energy, cold) is emitted within the balloon and is passed to the outer side thereof. The system of the present invention operates without a balloon whereby it may be much more compact.
A laser applicator is described in U.S. Pat. No. 6,676,656 B2. Among other applications, this laser applicator serves for the treatment of arrhythmias. It comprises a hand-held housing with a sheath extending from the distal end thereof, which sheath contains a light guide. The sheath may be wound around a plurality of pulmonary veins, wherein radiation from the decoupling portion of the light guide impinges on the wrapped pulmonary veins and scleroses the same. The laser applicator is suitable only for use at the open heart, in particular in connection with the placing of bypasses. This is a major limitation of the applicability of the device. Further, larger distances occur between the light guide and the target region to be treated, so that a comparatively high irradiation power is required.
DE 198 03 460 C1 describes an application device for the treatment of biological tissue through laser radiation. In a distal end portion, a light guide enclosed by a sheath layer is at least partly free of this sheath layer such that the laser radiation is emitted sideward from the fiber core with a homogenous propagation. At the exit points. The light guide has light-scattering particles. The distribution of the intensity of the energy exiting from the strand can be influenced by changing the particle density.
DE 101 29 029 A1 describes the introduction of laser light into a optical fiber including scattering bodies to obtain a diffuse lateral irradiation.
DE 44 07 498 C2 describes an optical waveguide for lighting purposes that decouples light sideward. For this purpose, the surface of the optical sheath is textured.
Finally, EP 1 527 798 A2 describes a laser applicator for photo therapy, which also includes scattering particles in a distal end portion of the optical fiber.